Abbott's appointment has sparked a heated reaction in some quarters, with critics saying he is well known for holding misogynistic and homophobic views, as well as drawing attention to his scepticism on climate change.

After Prime Minister Boris Johnson came out in support of the 62-year-old, Abbott said he was "only too keen" to help the UK and looked forward to helping facilitate trade deals "between Britain and other countries, including Australia".

"A UK-Australia trade deal, maximising the movement of goods, services and people is clearly in the best interests of both our countries," Abbott said in a statement on Twitter.

"It's important for the wider world that Britain make the most of its post-Brexit opportunities and I am proud to be playing a part.

"My government finalised trade deals between Australia and China, Japan and Korea. I'm looking forward to bringing that expertise to bear as Britain works towards mutually beneficial improvements with its major trading partners."

Opposition trade spokeswoman Emily Thornberry said Abbott was "not the right person to advise the UK on trade policy" due to his "history of offensive comments" and lack of experience.

"He's never been involved in detailed trade negotiations, he thinks that issues like climate change and workers' rights are just not important and during the two years that he was prime minister of Australia he was personally responsible for killing off Australia's car industry," she told Times Radio on Saturday.

Johnson defended Abbott, heralding his status as a former leader of "freedom-loving" and "liberal" Australia.

Former Australian foreign minister Alexander Downer, who was also high commissioner to the UK, said criticism of his former ministerial colleague was just "politicking".

Asked about Abbott's past comments about women, Downer BBC Radio 4's Today program: "It is an attempt to try to denigrate Tony Abbott by searching, searching, searching for any quote that can be found (but) the truth is he is not a homophobe - his sister is gay and has stood up for him, very strongly for him over this issue.

"He is not a misogynist, he has appointed many women to positions - he was appointed to this position by a woman.

"I don't think it stacks up. I think it's just party politicking."

The Department for International Trade formally announced on Friday Abbott would form part of the new-look Board of Trade.

It stressed advisers to the board would have "no direct role in striking trade deals".

The UK is looking to agree its own trade agreements after leaving the European Union in January.

It is conducting negotiations with the US, Japan, New Zealand and Australia.

Australian Associated Press